


Adventures in Childhood

by Fighting4Fandoms



Category: The Umbrella Academy (TV)
Genre: Age Regression/De-Aging, Family, Family Bonding, Family Feels, Family Fluff, Gen, Number Five | The Boy has PTSD, Reginald Hargreeves' A+ Parenting
Language: English
Status: In-Progress
Published: 2020-08-10
Updated: 2020-08-12
Packaged: 2021-03-06 07:00:38
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 2,555
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25829323
Author URL: https://archiveofourown.org/users/Fighting4Fandoms/pseuds/Fighting4Fandoms
Summary: Fed up with having his prepubescent body, Five decides to take action but when did anything ever go according to Five's plan?Cue baby Five!
Relationships: Number Five | The Boy & Allison Hargreeves, Number Five | The Boy & Ben Hargreeves, Number Five | The Boy & Diego Hargreeves, Number Five | The Boy & Grace Hargreeves, Number Five | The Boy & Klaus Hargreeves, Number Five | The Boy & Luther Hargreeves, Number Five | The Boy & Vanya Hargreeves, The Hargreeves Family
Comments: 39
Kudos: 215





	1. This is Child's Play!

**Author's Note:**

> Don't worry guys! I am still doing the one shots but this came to me ... in the bath again of all places...

To be completely honest... Vanya was not surprised to see the sight that she and her siblings were presented with. 

Over the past few days, all they saw of Five was him scrawling over the chalkboard that Allison had bought for him - so that his walls could actually survive - he muttered to himself. That itself wasn't strange to see or hear but he was acting more frantic... more deranged and desperate. 

"I don't like this." Everyone heard Luther say over and over again as the week dragged on. 

Vanya looked to her siblings in the kitchen when they heard the minor explosion.   
"What-"

"Shit!" Klaus fell off the table with a shriek. 

"What the hell was that?" Allison looked out of the kitchen, "What the hell did Five do now?" 

"Erm..." Diego was not the only one of their siblings to be rendered speechless. 

They had clambered up the stairs, almost tripping over themselves as they reached Five's bedroom at the top of the house. The blue flashing had stopped and the smoke had been vanquished. 

"Erm..." Luther said too. 

"So," Ben whispered to Klaus, "I swear Five wasn't _this_ small..." 

Underneath the pile of Five's uniform was a little baby, probably a little over a year old, sucking on his chubby little fist, giggling to himself. 

"Five?" Allison knelt in front of the little boy. 

She looked into his eyes of the boy and his eyes joined hers for a moment before he put his hand against her cheek, smiling innocently. 

"Tree!" 

"Huh?" Diego tilted his head, "What does he mean?" 

"It's Five..." Vanya gasped softly. 

"I think he's saying, 'Three'." Klaus pointed out. 

"At least he recognizes us." Allison stroked his head, that was one positive to come out of this. 

What the hell did Five do? Allison offered her arms to him and Five crawled over and put his arms around Allison's neck, Allison picked up his blazer to wrap around his naked body. 

"Right, we're going to need baby stuff." Allison shrugged, "Klaus, you and Vanya go and get clothes, diapers, food, things like that." 

"What should we do, sis?" Diego asked. 

"Go and get Mom." Allison ordered. "She'll know what to do." 

Allison watched her siblings leave Five's bedroom and she turned her attention back to her brother, noticing that she was staring at the sky outside, in complete awe. 

"Do you like the sky, Five?" 

Five babbled, giggling, pointing his chubby finger at the window. "Tree, Tree!" 

"You wanna go over there?" 

Five nodded his head, Allison smiled warmly and did as he asked, pulling the blazer further up. 

"Allison, dear, what is going on?" Grace's voice could be heard from the doorway. 

Five's head shot over to the sound of Grace's voice.   
  


Now, as you may well know, Grace didn't come into the children's lives until they were four but there was something about her that Five liked. He smiled, showing his gums, his small eyes twinkling. 

"Mama!" Five pointed at her, smiling brightly. 

"Oh, Five," Grace put her hands on her hips, "What mischief have you caused now?" 


	2. What To Do

**Summary for the Chapter:**

> With Five in his much younger body, it's up to his siblings to figure out what to do.

With Five on Grace's hip, their mother explained what had happened and what could be done to remedy it. 

"You're joking?" Diego dipped his head forward. 

Grace, to sum it up, explained that by trying to force his body to age with the incorrect calculations, his body did the exact opposite of what Five had intended. 

"Will he be back to normal?" asked Luther, "well, 13 version of him?" 

"Yes." Grace nodded, stroking Five's chubby cheek. "However... it will take a while for his body to return to normal." 

"How long?" Luther asked. 

"It's difficult to say." 

Five, unknown of the situation at hand, giggled to himself and babbled in his siblings' direction, pointing at Klaus in particular. 

"Four!" Five yelped. "Four!" 

"I think Five wants you." Ben snorted to himself, Klaus hissed at him. 

"I'm not good with kids." Klaus tried to back off but Ben pushed him forward, unseen by everyone else of course. 

"Four?" Diego nudged him, "You gonna hold Five?" 

"Piss off." 

"Language." Grace held out Five for Klaus to hold. 

Klaus, reluctantly, took Five and cradled him, Five smiled - a strange sight for everyone, he so rarely smiled. It was a beautiful smile because it radiated Five's innocence which he no longer had as an adult. It was strange to think that the baby in Klaus' arms was a notorious killer and technically a 58 year old. He was older than all of them but now possessed the body of someone much, much younger. 

"Did you guys get clothes?" Allison asked Klaus and Vanya. 

Vanya nodded, "Clothes, food, diapers. Everything you said." 

"Good." Allison sighed, she really needed a sit down. 

"So," Diego folded his arms, "What are we supposed to do?" 

"Look after our brother, obviously." Luther sighed, "it's going to be hard work but Five would do, has done, the same for all of us more than once." 

"Luther's right." Klaus murmured, staring at the baby in his arms, "We're just going to have to work together, I don't care for how long." 

"I brought down his old crib from the attic." Luther gestured to the door, "I put it in his room." 

"I can't believe Dad kept all of those." Vanya smirked, it was a strange concept. 

Five yawned, blinking his little eyes. 

"I'll go and put Five to bed," Grace whispered, taking him from Klaus, "Can you children go and help start dinner?"

"Yes, Mom." The others chimed in unison. 

Allison followed the others from behind, she could see Grace cradle Five in her arms, singing a sweet, gentle tune. 

_La la lu_   
_La la lu_   
_Oh, my little star sweeper_   
_I'll sweep the stardust for you_   
  
_La la lu_   
_La la lu_   
_Little soft fluffy sleeper_   
_Here comes a pink cloud for you_   
  
_La la lu_   
_La la lu_   
_Little wandering angel_   
_Fold up your wings, close your eyes_   
  
_La la lu_   
_La la lu_   
_And may love be your keeper_   
_La la lu_   
_La la lu_   
_La la lu_   
  
_There now, little star sweeper_   
_Dream on_

The last thing Allison saw of them before she walked downstairs was Five putting his little head against Grace's shoulder, babbling to himself as he dreamt off into a deep slumber 

**Notes for the Chapter:**

> Yep, the song's from Lady and the Tramp. I love that song!


	3. Peekaboo!

**Summary for the Chapter:**

> Diego and Klaus have to babysit Five

"If anyone was going to tell me that Batman and Robin would be babysitting murder baby over here," Ben smirked from the bar he was sitting on, "I would have never believed them." 

By the sofas on the floor, Five was sitting on the floor, sucking on a pacifier, with Klaus and Diego sitting opposite from him. Klaus was actually finding looking after baby Five a lot more fun than he realized. Diego, on the other hand, had become the nervous wreck that Klaus thought he would be himself. 

Diego and Klaus both watched Five with a curious nature. You see, when Five was a baby the first time... so were they, obviously. Klaus and Diego both didn't have much experience with babies but they had no choice but to watch Five. 

Allison, Luther and Vanya were out shopping to finish getting baby supplies, furniture and groceries whilst Diego and Klaus were watching Five. Grace helped them out whilst cleaning the house and cooking lunch but it seemed as though Klaus and Diego could manage perfectly. 

"Mama mama mama." Five babbled to himself, trying to crawl away when Klaus and Diego weren't watching. 

"Fivey, come back!" Klaus grabbed him, lifting him into the air. 

Instead of crying, like his brothers were expecting him to, Five giggled, waving his chubby fists in the air. His green eyes sparkled in the light when Klaus popped him into Diego's lap. 

"Hey there, buddy." Diego cooed at him. 

Five smiled, showing off his gums. 

When he was a baby the first time, he was always smiling. He would be giggling, babbling and laughing all the time. His nanny came to the conclusion that it wasn't because he was just happy, it was because Five was planning mischief and no one was none the wiser. 

"He!" Five put his hand on Diego's face. "Two Two!" 

"Aww." Klaus fawned, "He's saying your name."

"It's not that hard to say." 

"Meh." Klaus shrugged. "Hey, Fivey, want to play a game?" 

Five turned his eyes to Klaus and laughed. Klaus took that as a 'yes.' Diego put him back where he was before. Klaus folded his legs and put his hands over his eyes, nudging Diego to do the same. 

"Where's the baby?" Klaus chimed. "There he is!" 

Five giggled, patting the ground. 

"Your turn." 

"Where's the baby?" Diego played along. They waited for a few minutes, "Peekaboo!" 

When Klaus and Diego unvieled their eyes they gasped, their eyes widening, Five wasn't there. 

"Where's Five?" Diego looked around. 

"Crap! Did we lose him?!" 

"Shiiiiiiiiit." Diego jumped to his feet. "He couldn't have gone far!"

Rummaging around in hsyterical panic, Diego and Klaus searched into every nook and crevice of the living room. Behind the bar: no. Under the sofa: no. 

"Shit!" Diego hit his knee, "You don't think that he blinked... do ya?" 

"Christ on a cracker!" Klaus yelped. "He could be anywhere!" 

"You search the downstairs!" Diego shouted, already running out of the living room and flying up the stairs. 

Diego searched every room upstairs and Five was nowhere to be seen. Meanwhile, Klaus tried to search the downstairs rooms without alerting Grace which wasn't an easy thing to do when your mom was a robot. 

"Five!" Diego shouted in a whisper. He listened out carefully, even holding his breath, he could hear the faint sound of babbling from their father's bedroom. 

The door opened, the hinges groaning. 

"Five?" 

Reginald's room hadn't been touched since Diego had interrogated Luther that day and Diego felt so small in that room, even though his father was dead. He hated his father with a passion. No matter what Diego did, he could never appease his ego. 

"Five?" 

He heard a babbling noise and there he was. The little boy was sitting on the windowsill, gently tapping the windows. 

"There you are." Diego said softly. He sat down on the chair beside the window and watched his brother with fascination. It was no surprise that Five had been intelligent as an infant. He mastered walking and talking before he did. Five didn't have a first word. He had a first sentence instead. 

"You okay?" Diego asked him. 

The way that Five looked at him was innocent yet so sad at the same time. 

"Dada?" Five pointed to the bed. 

Oh. 

Diego gulped. He really wish that he didn't have to explain. It seemed as though that Five had no idea what had happened. The way that Five's memories were working were all jumbled. He could remember Grace even though he hadn't met her at this age. He only called his siblings by their numbers. Yet, he didn't remember that their father was dead. Why did it have to be Diego to explain to a child incapable of understanding the concept of death. If only it was Klaus instead. Klaus had always been able to see the dead, it meant many restless nights for Number Four as a baby. 

"Dad isn't here anymore, Five." 

Five scrunched his face up, a mixture of confusion and sadness. 

None of them could remember what Reginald was like with them as babies but Diego doubted that he was all warm and cuddly. He never had been. 

"Two Two." Five curled and uncurled his fists, trying to reach out for Diego. 

"Come here." Diego picked him up off the windowsill and sat him on his knee. "I don't know if you can understand me, or anything, Five but I just wanted to say that you're not as bad as you think you are." 

Five smiled up at him, leaning his head against the man's chest. 

"Oh thank goodness," Klaus clapped from the doorframe. "Is he okay?" 

Diego nodded silently. 

"Four!" Five whisper-shouted. 

"Looks like he wants his bros." Ben smiled from beside Klaus. "He's quite cute, isn't he?" 

"Well, he's not murdering anyone, Benny boy." 

"Sis!" Five mumbled to himself. 

Klaus' fist turned blue and Ben's blue form sat himself down on the floor, "Hey, Five." 

"Sis!" 

"You wanna hold?" Diego asked. 

Ben nodded and held out his arms, smiling when Five didn't drop through him. Five smiled, completely unfazed by his brother's ghostly form. 

"This is nice." Ben sighed, being content with just sitting with his brothers in the silence of their late father's bedroom. 


	4. We're Supposed to be Twins

Luther had a weird sleep schedule. 

He would go to sleep but he would always wake up at 3 in the morning, before going back sleep and waking back up at half 5. For some reason. Luther didn't understand it and he really couldn't be bothered to question it. At the time of 3, Luther would check on his siblings, going from room to room to check that they were still there. He would breathe a sigh of relief when he saw them there. 

Reaching Five's room, he expected to see the baby sleeping in his crib but no, Five was sitting at the window, staring up at the night sky. Furrowing his eyebrows, Luther approached him and crouched behind him.   
"Can't sleep too, huh?" 

Five shook his head slightly, not even jumping at his brother's voice. 

"I'm not sure if you know or not," Luther pointed up at the sky, "but I lived up there for a while." 

Five's eyes went big, his little mouth dropping. 

"You want a drink?" Luther asked, smiling when Five smiled, "Come on, buddy." 

He picked him up, it was funny that he could fit him in just one hand, and walked down the stairs to the kitchen, being quiet so that no one woke up. 

He sat Five in his high chair that Allison had bought and warmed up a bottle of milk for Five. He could hear Five babble to himself and it reminded him of a time when Five would mutter to himself. He did it a lot because Five's brain was often crammed and it was a way to alleviate it. 

"Here ya go." Luther said. Five couldn't quite fit his hands around the bottle and his face scrunched up with irritation. 

"Oh, right, sorry." Luther apologized, He picked Five up and cradled him in his arm, putting the bottle to his mouth. Five suckled on it hungrily, his little eyes focusing on the milk that was slowly disappearing from the bottle. 

"You must have been hungry." Luther chuckled. 

"Ah!" Five burped when he was done, Luther put the bottle down on the table. 

"Mama!" Five pointed at the doorway where Grace was standing. 

"Mom!" Luther exclaimed. "I thought you were charging." 

"Oh, I was." Grace smiled. "I could hear you two down here, I came to see if you needed anything." 

"Mama! Mama!" Five pointed at her, giggling almost manically. 

"I think Five wants you." 

Grace picked him up from Luther and kissed Five's head. "Why don't you go back to bed, Luther dear, I can sort Five out." 

"Are you sure?" 

"Of course," Grace answered, "You need sleep." 

As if on cue, Luther yawned, "yeah, night Mom." 

"Good night dear." 


End file.
